Отправка сообщений через Pushbot возвращает ошибку с кодом 409

Доброе время суток,

Выполняю такой код:

        try
        {
            URL url = new URL("https://api.pushbots.com/push/all");
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestProperty("x-pushbots-appid", "585118444a9efa5cbf8b4567");
            conn.setRequestProperty("x-pushbots-secret", "4e88d8484d9c8fac55090dbc96dfbe53");
            conn.setRequestProperty("Content-Type", "application/json");
            conn.setRequestMethod("POST");
            BufferedReader br = new BufferedReader(new InputStreamReader( (conn.getInputStream())));
            String output;
            System.out.println("Output from Server .... \n");
            while ((output = br.readLine()) != null) {
                System.out.println(output);
            }
            conn.disconnect();
            logger.info("Push ok");
        }
        catch(Exception e)
        {
            e.printStackTrace();
            System.out.print("1");
            logger.info("Push error");
            logger.info(e.toString());
        }
        return "Ok";
    }

Получаю ошибку: java.io.IOException: Server returned HTTP response code: 409 for URL: https://api.pushbots.com/push/all